A drawing is often copied for engineering, architectural and other lines of endeavor. The copying of drawings has been done for many years. Almost everyone is familiar with the copying of a drawing to make a blueprint. For example, in the construction of a building blueprints are prepared to assist the contractor and the artists to construct the building according to plan. The same can be said with respect to the making of a boat, a trailer, a farm implement, furniture and the like.
A well-known form of copying is with a blueprint. An engineering firm and an architectural firm have blueprint machines. The drawing and the sensitized copy base are placed in an overlying relationship. Then, the drawing and the copy base are moved around a curve or a roller and exposed to a high intensity light. The combination of the drawing and the copy base move so as to fold back on themselves. The copy of the drawing on the copy base or on the sensitized base is not a true copy of the drawing. The copy of the drawing is distorted because of the travel of the drawing and the copy base around the curve or roller.
Another manner of making a copy of a drawing is to place the drawing on the copy base flat. The drawing and the copy base overlie each other. There is used a number of lights for exposing the copy base. With the number of lights it is not possible to secure an even distribution of the light rays. As a result there appear to be hot spots on the copy base or the exposed base. These hot spots result in an uneven exposure of the copy base and an uneven blueprint. Also, the size of the copy is limited by the size of the frame which can receive the drawing and the copy base. Most frames are not large frames and therefore most drawings and copies are restricted in size. The light should have the same time of exposure. If one light fails then it is necessary to replace all of the lights so that all of the lights have the same kind of exposure. If all of the lights have the same time of exposure then there is a better opportunity for more even distribution of light. As is realized many lights are expensive and many lights use considerable electricity.